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So. I'm working on this house after another tech had trouble figuring out the problem.

Has a pair of Carrier 58ZAV's in a indoor closet next to a water heater.
The inducer draft monitor (limit switch) trips randomly. Tech does the typical check and repair on the baffle that sometimes comes lose inside it and checked the flue and thought was ok, but problem continues.

So they send me. H/O says problem has been happening since home was new a few years ago. I noticed that the two furnaces and water heater were in a closet with an airtight door. So I closed gthe door behind me and ran both furnaces at once to test.

Here I have my bead thermometer in at the opening so I can check temp as a sign of flue gases coming out rather than fresh air entering.

Temp is going over 200 degrees. Not good. Meter hit around 270 degrees as the limit tripped in front of me. Not good.
I re check the inside baffle that comes lose in these, it's ok. I re checked the flue cap, it's ok.
Next thing I think is, ..."is it getting enough combustion air"?
I then check the upper and lower combustion air vents. Followed the pipe into the attic, all ok there. Go up on the roof and decided to pop open one of the t-tops over the fresh air vents... bingo.

Lazy as bast@rds just throw this sh*t together don't they???

5 minutes later with my snips and hammer and it's all fixed.

Both vents were this way. After the repair I could FEEL the air drafting in and out of the vents and the flue draft never went over 130 degrees after that.

Now. While I was fixing that problem I noticed
the "Environmental Controls" box which you can see in the above picture (of my meter) on the wall to the right. I knew there would be a Energy Recovery Ventilator system in this house and when I was in the attic, sure enough THERE it was in accessable by the home owner!

These things are USUALLY installed by our co in the ceiling with a drop open door or something. NOT just thrown in the attic in between trusses where the H/O will surely never go!

Any of you familiar with these things knows you have to pull out this heat exchanger to CLEAN it periodically! It is impossible with it installed too close to the trusses!
Idiots!

Oh well. Nothing that great here for you but this has become a GREAT place to vent when I see this sh*t and unfortunately, some times the management happens to find out I post here. Oh well. It's not MY sh*ty work I post here. They just send me to work on the crap!
If I could find out who was RESPONSIBLE I would send photos to their office! :-)

... attic install in itself is not the problem

Originally posted by PaysonHVAC These things are USUALLY installed by our co in the ceiling with a drop open door or something. NOT just thrown in the attic in between trusses where the H/O will surely never go!

...

Any of you familiar with these things knows you have to pull out this heat exchanger to CLEAN it periodically! It is impossible with it installed too close to the trusses!
Idiots!

I agree that in this case the installation was really, really bad. However, I don't see anything wrong with an attic install in itself - inform the HO what's up there and have them clean the HX core of the ERV/HRV just as you would the filters in the AH. If the HO is too dumb to maintain their stuff, then it's their fault if the house's value, or their life, is in jeopardy.

OK two probelms with some of that advise. Not your advise, but the situation here.

The ERV is in a attic with NO light, no catwalk, no access to even OPEN the front panel to pull out the heat exchanger to clean. It was like the installers set it in between the trusses as if it NEVER had to be touched again.

Second problem with some of these... our company installed it. I told the suprivisor, but unlikely anything will ever get done because the co would have to open their mouth to the HO. Fat chance on that. But wait until ANOTHER co. finally goes to this house. Then the HO will hear for the 1st time that he has an appliance shoved into an un accesable section of the attic that needs regular attention.

I'm stuck holding my tounge as usual.
But I'm not going to stop from venting over here :-P